And what a day at the office it was: In the pic, which she captioned "Work day," Kanye West's fiancée wears a sheer, midriff-baring ensemble that highlights her ample curves while drawing attention to her trim waist.

Kim has been working hard at her new figure: The new mom, who recently told PEOPLE that her pregnancy was "a lot tougher than people saw on my show or from magazines," has been on a strict Atkins-based diet and workout regimen. It's clearly working: So far, she's already shed 50 pounds of baby weight.